Influence of cytokinins, silver nitrate (AgNO) and auxins on plant regeneration from cucumber was investigated. The cotyledonary node explants were cultured on MS medium augmented with various concentrations (0.5-2.5 mg l) of 6-benzyl amino purine (BAP) and kinetin (KIN) for shoot bud induction. BAP at 1.5 mg l was found to be the best concentration for induction of high frequency of multiple shoots (98.4%). Interestingly, maximum percent of multiple shoot regeneration (100%) as well as number of shoot buds (54.6 shoots/culture) was recorded on MS medium containing the combination of 4.5 mg l AgNO and 1.5 mg l BAP. Multiple shoot bud regeneration frequency as well as the number of shoots was positively correlated with the concentrations of AgNO. Addition of silver nitrate in the medium not only enhanced the rate of multiple shoot bud regeneration but also elongation of shoot buds was observed. The highest percent of rooting (96.2%) was noticed on a medium containing the combination of indole 3-butyric acid (IBA), 1.5 mg l and KIN 0.5 mg l. Acclimatized plantlets were successfully established in the field where the survival rate observed was 72%. The RAPD profiles of in vitro regenerated plants were found to be highly monomorphic and identical banding pattern with mother plant. DNA fingerprinting results confirmed that the tissue culture plantlets were found to be true-to-type. The present study describes efficient protocol for high frequency plant regeneration via adventitious shoot organogenesis in cucumber.

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The present study describes a rapid method for synthesis of metallic silver nanoparticles using callus (CAgNPs) and leaf extracts (LEAgNPs) of Cucumis sativus and evaluation of its wound healing activity in rat model. The prepared silver nanoparticles showed a peak at 350 nm corresponding to the surface plasmon resonance band. The FTIR spectroscopy measurements showed the presence of the possible biomolecules. X-ray diffraction analysis confirmed the crystalline structure of the synthesized silver nanoparticles. TEM images showed the size of the synthesized CAgNPs with diameter ranged from 21 nm to 23 nm with polygonal shape whereas, in the case of LEAgNPs, spherical shape was noticed with an average size between 11 nm and 19 nm. The EDX results indicated the chemical composition at specific locations on synthesized nanoparticles. Furthermore the topical application of ointment prepared using synthesized AgNPs was found to show enhanced wound healing activity in Wistar albino rat model. By the 21st day, the ointment base containing 5% (w/w) of silver nanoparticles showed 100% potential wound healing activity than the standard drug as well as control bases. Results strongly showed that the ointment base containing LEAgNPs was found to be very effective in wound repair mechanism in the experimental rats.

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